1. Field of the Invention
The present invention relates to an improvement of an IC card device which prevents its IC chip from breaking.
2. Description of the Related Art
Typical conventional IC cards have an IC and a contact portion integrated into an IC module to provide a unit structure. With the use of such a unit structure, no wirings are laid under the contact portion.
In the case where multiple IC cards and/or parts such as a keyboard and a display need to be arranged, however, it is not possible to integrate all of them into an IC module to provide a unit structure. Therefore, the ICs and the other components are arranged separate from the contact portion as disclosed in, for example, U.S. Pat. No. 4,972,580. This arrangement requires wiring between the ICs and the other components as well as wiring between each IC and the individual contacts. There is not much space left for the wiring due to the mounting space required for the ICs and components. When the ICs and the other components arranged with the contacts in between, the wirings to connect the ICs to the components cannot be laid straight, but should undesirably run around the contacts.
U.S. Pat. No. 4,697,073 teaches contact wirings laid on the top and bottom surfaces of the printed circuit board and connected to multiple segments lying on the topmost surface of the board. The contact wirings are connected to the main chip in a hole. In this case, since contact wiring patterns lie directly below the respect contacts and no contact wiring pattern lies directly below the space between contacts provided side by side on the surface of the board, the former portion of the IC card is made relatively thick while the latter portion of the IC card is made entirely thinner than the other portion. In addition, the printed circuit board on the topmost layer of the IC card has an opening formed in order to expose the contacts from the surface. When external force is applied to the IC card, therefore, stress is likely to concentrate on the thin portion, which may damage the main chip. The conventional IC card having an IC and components arranged separate from the contacts therefore has a problem on the mechanical strength in addition to the aforementioned shortcoming on the laying of the wirings.